Session coordination for auto-scaled virtualized graphics processing

ABSTRACT

A graphic session coordinator is established to enable remote virtualized graphics operations on behalf of a set of graphics request generators. A request generator submits a graphics session request to the session coordinator. A configuration operation is performed at one or more routing devices to enable graphics operation request packets from the request generator to be delivered to a first remote virtualized graphics device and to enable graphics operation response packets to be transmitted to a destination.

This application is a continuation of U.S. patent application Ser. No.15/439,751, filed Feb. 22, 2017, which is hereby incorporated byreference herein in its entirety.

BACKGROUND

Many companies and other organizations operate computer networks thatinterconnect numerous computing systems to support their operations,such as with the computing systems being co-located (e.g., as part of alocal network) or instead located in multiple distinct geographicallocations (e.g., connected via one or more private or publicintermediate networks). For example, distributed systems housingsignificant numbers of interconnected computing systems have becomecommonplace. Such distributed systems may provide back-end services toservers that interact with clients. Such distributed systems may alsoinclude data centers that are operated by entities to provide computingresources to customers. Some data center operators provide networkaccess, power, and secure installation facilities for hardware owned byvarious customers, while other data center operators provide “fullservice” facilities that also include hardware resources made availablefor use by their customers. As the scale and scope of distributedsystems have increased, the tasks of provisioning, administering, andmanaging the resources have become increasingly complicated.

The advent of virtualization technologies for commodity hardware hasprovided benefits with respect to managing large-scale computingresources for many clients with diverse needs. For example,virtualization technologies may allow a single physical computing deviceto be shared among multiple users by providing each user with one ormore virtual machines hosted by the single physical computing device.Each such virtual machine may be a software simulation acting as adistinct logical computing system that provides users with the illusionthat they are the sole operators and administrators of a given hardwarecomputing resource, while also providing application isolation andsecurity among the various virtual machines. With virtualization, thesingle physical computing device can create, maintain, or delete virtualmachines in a dynamic manner. For some applications implemented usingvirtual machines, specialized processing devices may be appropriate forsome of the computations performed—e.g., some algorithms may requireextensive manipulation of graphical data.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 illustrates an example system environment for virtualizinggraphics processing in a provider network, according to one embodiment.

FIG. 2 illustrates example components of virtualization hosts andgraphics hosts which may be used for virtualizing graphics processing,according to at least some embodiments.

FIG. 3 illustrates an example system environment in which auto-scaledvirtualized graphics operations may be configured at a provider networkfor graphics request generators external to a provider network,according to at least some embodiments.

FIG. 4 illustrates example programmatic interactions which may be usedto establish or modify an auto-scaled virtualized graphics resourcegroup, according to at least some embodiments.

FIG. 5 illustrates example programmatic interactions associated withestablishing sessions for virtualized graphics operations, according toat least some embodiments.

FIG. 6 a and FIG. 6 b illustrate respective examples of addressingschemes which may be used for packets comprising graphics operationrequests, according to at least some embodiments.

FIG. 7 a and FIG. 7 b illustrate respective examples of intra-sessionauto-scaling changes, according to at least some embodiments.

FIG. 8 illustrates example categories of graphics resource pools whichmay be established at a provider network, according to at least someembodiments.

FIG. 9 is a flow diagram illustrating aspects of operations that may beperformed to support automated scaling of virtualized graphicsresources, according to at least some embodiments.

FIG. 10 is a block diagram illustrating an example computing device thatmay be used in at least some embodiments.

While embodiments are described herein by way of example for severalembodiments and illustrative drawings, those skilled in the art willrecognize that embodiments are not limited to the embodiments ordrawings described. It should be understood, that the drawings anddetailed description thereto are not intended to limit embodiments tothe particular form disclosed, but on the contrary, the intention is tocover all modifications, equivalents and alternatives falling within thespirit and scope as defined by the appended claims. The headings usedherein are for organizational purposes only and are not meant to be usedto limit the scope of the description or the claims. As used throughoutthis application, the word “may” is used in a permissive sense (i.e.,meaning having the potential to), rather than the mandatory sense (i.e.,meaning must). Similarly, the words “include,” “including,” and“includes” mean including, but not limited to. When used in the claims,the term “or” is used as an inclusive or and not as an exclusive or. Forexample, the phrase “at least one of x, y, or z” means any one of x, y,and z, as well as any combination thereof.

DETAILED DESCRIPTION

Various embodiments of methods and apparatus for managing sessions forgraphics operations performed using remote virtualized graphicsresources in a scalable policy-driven manner are described. According toone embodiment, a network-accessible virtualized graphics and computingservice (VGCS) may implement programmatic interfaces enabling clients torequest allocation and instantiation of guest virtual machines which canbe used to execute applications. Such guest virtual machines may also bereferred to as “application compute instances” in various embodiments.Some of the applications of the clients may include substantial amountsof graphics-related processing—e.g., for game streaming, 3D applicationstreaming, scientific visualizations/simulations, server-side graphicsworkloads, rendering, financial modeling, and/or engineering designtasks. To serve clients with such applications, in various embodimentsthe VGCS may configure remote virtualized graphics devices (such asvirtual graphics processing units or GPUs) which are available fornetwork access from application compute instances. In at least someembodiments, a VGCS may be implemented at a provider network. Networksset up by an entity such as a company or a public sector organization toprovide one or more network-accessible services (such as various typesof cloud-based computing, storage or analytics services) accessible viathe Internet and/or other networks to a distributed set of clients maybe termed provider networks in one or more embodiments. A providernetwork may sometimes be referred to as a “public cloud” environment.The resources of a provider network (and/or a VGCS) may in some cases bedistributed across multiple data centers, which in turn may bedistributed among numerous geographical regions (e.g., with each regioncorresponding to one or more cities, states or countries).

The graphics-related workload of a client may change over time in someembodiments, sometimes fairly quickly depending on the kinds ofapplications being run, making it difficult to predict in advance theprecise amount of remote virtualized graphics processing capabilitiesthat may be required at some future time. In various embodiments, theVGCS may implement programmatic interfaces which can be used to requestthe establishment of auto-scaled groups of remote virtualized graphicsdevices, such that the VGCS may automatically deploy (or un-deploy)virtualized graphics devices as the graphics requirements of the clientchange. After an auto-scaled group of graphics resources is established,in various embodiments requests for starting and terminating graphicssessions may be sent to a graphics session coordinator associated withthe auto-scaled group, as described below. A respective scaling policy,e.g., defining constraints regarding the maximum and/or minimum numbersof different categories of remote virtualized graphics devices which canbe deployed as part of an auto-scaled group, and/or definingprovisioning rules to be used to add/remove remote virtualized graphicsdevices, may be associated with individual ones of the auto-scaledgroups in various embodiments. A number of different provisioning modesmay be supported for such auto-scaled groups, such as exclusive orreserved provisioning mode, best-effort provisioning mode, and the like,which may impact the manner and timing of allocations of remotevirtualized graphics devices, as described below in further detail.

In response to a programmatic request to establish an auto-scaledgraphics resource group with an associated scaling policy, in variousembodiments the VGCS may establish a graphics session coordinator (GSC)for the requesting client. In at least one embodiment, one or moremetadata entries corresponding to the GSC may be stored in aconfiguration database of the VGCS, including for example an objectrepresenting a virtual network interface with one or more networkaddresses or endpoints. The virtual network interface may be assignedone or more network addresses in some embodiments (e.g., InternetProtocol (IP) version 4 or version 6 addresses), at least some of whichmay be accessible from the application compute instances from whichgraphics operation requests are expected. In some embodiments, insteadof or in addition to virtual network interfaces, one or more physicalnetwork interfaces may be set up for the GSC. After the GSC has beenconfigured, requests for establishing graphics operations sessions maybe directed from the individual application compute instances of theclient to one or more of the GSC network addresses in variousembodiments. In at least some embodiments, a given graphics operationsession (which may also be referred to simply as a graphics session) maycomprise the transmission of some number of graphics operation requestsfrom an application compute instance (or some other graphics requestgenerator), the execution of the requested operations at one or moreremote virtualized graphics devices, and the transmission of some numberof responses comprising results of the requested graphics operationsfrom the remote virtualized graphics devices to specified resultdestinations (where the destinations may in some cases differ from therequest generators). In some embodiments, a request for establishing agraphics session may be referred to as a request to programmatically“attach” one or more remote virtualized graphics devices, and acorresponding “detach” request may be used to terminate a session.

If the establishment of a requested session would not violate thescaling policy associated with the set of application compute instancesfor which the GSC has been set up, the VGCS may cause one or moreconfiguration operations at a routing service or routing layer, suchthat packets containing graphics operation requests may be directed toone or more remote virtualized graphics devices of the auto-scaled groupduring the session, and packets containing results of those graphicsoperations may be directed from the one or more remote virtualizedgraphics devices to one or more destinations identified for the session.Depending, for example, on the provisioning mode associated with theauto-scaled group, in some embodiments the remote virtualized graphicsdevice(s) for the session may have to be instantiated after the sessionrequest is received. In some cases, e.g., when an exclusive or reservedprovisioning mode is used, a pool of remote virtualized graphics devicesmay be established in advance, and one or more of the pre-establisheddevices may be allocated to an approved session in various embodiments.After the graphics operations of a given session are complete, in someembodiments the session may be terminated—e.g., either in response to anexplicit termination request, in response to determining that theapplication compute instance has been terminated, or based on somethreshold of inactivity with respect to the remote virtualized graphicsdevice used for the session. In various embodiments, the hardwareresources that were used for a remote virtualized graphics device duringa given session (or the remote virtualized graphics device itself) maybe re-used, e.g., in response to a request for a different session. Inat least one embodiment, before re-using graphics resources for adifferent session, at least a portion of memory and/or storage used forthe original session may be overwritten or cleared, so that applicationstate information is not passed from one session to another.

If deploying a remote virtualized graphics device for a requestedgraphics session would violate the scaling policy in effect, e.g., byexceeding the maximum number of remote virtualized graphics devicespermitted by the provisioning rules of the policy, the request may berejected by the VGCS in at least some embodiments. In at least oneembodiment, a message indicating an error and/or a violation of thescaling policy may be delivered to the session requester.

In some embodiments, auto-scaled deployment of graphics resources may beperformed at several different levels, including for example asession-initiation level and an intra-session level. Session-initiationlevel deployment may occur when new sessions are requested in someembodiments—e.g., new virtualized graphics resources may be instantiatedand deployed in response to a session establishment request whichindicates the types and counts of graphics devices required for thesession (or performance requirements of the session, which can betranslated into types and counts of graphics devices), as long as theprovisioning rules of the scaling policy are not violated. Intra-sessionlevel deployment of resources may occur in some embodiments, forexample, in response to measurements of usage of the graphics resourcesdeployed during an ongoing session. For example, if two remotevirtualized graphics devices are deployed for a given session, and theutilization level of the two devices exceeds a threshold for some timeperiod as the session proceeds, another virtualized graphics device maybe deployed for the session without requiring a corresponding request tobe sent to the VGCS, and the appropriate routing-related configurationchanges may be performed to enable graphics-related packets to flow toand from the added virtualized graphics device. In another example, iffour remote virtualized graphics devices are initially deployed for asession, and the average utilization level for the four devices remainsbelow another threshold for some time period, one or more of the devicesmay be removed or un-deployed, and the appropriate routing changes maybe initiated. A number of tools and/or a monitoring service may beemployed to keep track of metrics which may be used to make auto-scalingdeployment decisions in various embodiments.

In an embodiment in which exclusive provisioning of remote virtualizedgraphics devices is supported by the VGCS, pools of graphics resources(e.g., hosts comprising one or more graphics processing units or GPUs,or virtualized graphics devices instantiated at such hosts) may bereserved on behalf of respective clients. For example, if an auto-scaledgroup of up to a hundred remote virtualized graphics devices of aparticular category is requested in exclusive provisioning mode, a poolof one hundred such devices may be instantiated and used for subsequentsession requests originating at the client's application computeinstances in one embodiment. If a best-effort provisioning mode isindicated in an auto-scaling group establishment request, in variousembodiments the VGCS may not necessarily reserve the maximum number ofvirtualized graphics devices from a pool set aside for the client alone;instead, a shared pool of virtualized graphics devices and/orGPU-containing hosts may be used. In some embodiments, multiple sessionsmay be established using a single remote virtualized graphicsdevice—e.g., graphics requests generated by more than one applicationcompute instance may be fulfilled by a particular remote virtualizedgraphics device. In other embodiments, a given remote virtualizedgraphics device may only be used in a single-tenant manner, e.g., toperform graphics operations requested by no more than one applicationcompute instance.

The manner in which destination addresses are specified within graphicsoperation request packets of a given session may vary in differentembodiments. In at least one embodiment, when a session request directedto an endpoint of a graphics session coordinator GSC1 from anapplication compute instance ACI1 is accepted, connection parameterscomprising a destination IP address VGD-IPAddr assigned to a particularremote virtualized graphics device may be provided to ACI1. Subsequentrequest packets may indicate the VGD-IPAddr as the destination addressin such embodiments. In another embodiment, instead of using an IPaddress assigned to a virtualized graphics device, an address of thegraphics session coordinator GSC1 itself may be used as the destinationaddress for packets containing graphics operation requests during thesession, and routing components of the system may translate the GSC1address to the address of a virtualized graphics device selected for thesession. Analogous addressing schemes may be used for the packetcontaining results of the requested graphics operations in variousembodiments —e.g., either an address specific to a graphics requestgenerator such as an ACI may be indicated as the destination IP addressduring a session, or an address of the graphics session coordinator maybe indicated as the destination address. The terms “graphics-relatedtraffic”, “graphics-processing related traffic”, and “graphicsvirtualization-related traffic” may be used interchangeably to refer tothe network packets containing graphics operation requests and tonetwork packets containing results of the requested operations withrespect to at least some embodiments.

In at least one embodiment, a graphics session coordinator may havemultiple IP addresses associated with it, including zero or more privateIP addresses which are not advertised outside the provider network atwhich the VGCS is implemented, and/or zero or more public IP addresseswhich are advertised outside the provider network. In some embodiments,the ability to request and utilize graphics sessions may not berestricted to application compute instances located within the VGCSitself. For example, in some embodiments, graphics sessions whichutilize virtualized graphics devices of the VGCS may be established fromhosts within a client-owned network external to the provider network,and/or from hosts outside the provider network that are connected to thepublic portion of the Internet. In some such embodiments, the providernetwork may in effect implement a publicly-accessible graphics operationservice, in which applications running on various device connected tothe Internet can have their graphics processing performed in anautomatically scaled manner using the provider network's resources. Thehosts, devices or applications outside the provider network from whichgraphics operations requests are received and processed at the providernetwork may be referred to as “external” graphics request generators invarious embodiments, e.g., in contrast to the application computeinstances which may be considered “internal” graphics request generatorsfrom the provider network perspective. In at least one embodiment, agraphics session coordinator established for external graphics requestgenerators may be configured with at least one public IP addressaccessible from the external graphics request generators.

In some embodiments, a graphics driver or shim, for example provided byor downloaded from the VGCS, may be installed locally at the externalhosts from which graphics operation requests originate. Similar driversor shims may be used at application compute instances as well in variousembodiments. Such a graphics driver may, for example, be configured toinstantiate a local or “client-side” cache at which some results ofgraphics requests can be stored for re-use, thereby potentially reducingthe amount of graphics-related network traffic required for a givenapplication.

In at least some embodiments, a graphics session coordinator may be setup to provide an address or endpoint for requesting graphics sessions ingeneral, and may not necessarily be tied to a particular auto-scaledresource group or a scaling policy. For example, in one embodiment, agraphics session coordinator may be established in response to adetermination that remote virtualized graphics processing is to beenabled for a set of graphics request generators, without enforcingclient-specified auto-scaling requirements or rules. Such ageneral-purpose graphics session coordinator may be used in variousembodiments to set up and tear down graphics sessions in response torespective types of requests from graphics request generators.

In various embodiments, multiple types or categories of remotevirtualized graphics devices may be supported at a VGCS; such categoriesmay differ from one another along various dimensions such asperformance, vendor type and so on. In one embodiment, a client maychoose a virtualized graphics device type from several supported classesof virtualized graphics devices, and submit a request for a graphicssession in which one or more instances of the selected virtualizedgraphics device type are made accessible to a specified applicationcompute instance or graphics request generator. The classes of remotevirtualized graphics devices which can be used for a given session maybe indicated in the scaling policy associated with the auto-scaled groupbeing used in some embodiments.

In one embodiment, respective isolated virtual networks (IVNs) may beestablished on behalf of various clients at the VGCS. An isolatedvirtual network may comprise a collection of networked resources(including, for example, application compute instances) allocated to agiven client, which are logically isolated from (and by default,inaccessible from) resources allocated for other clients in otherisolated virtual networks. The client on whose behalf an IVN isestablished may be granted substantial flexibility regarding networkconfiguration for the resources of the IVN—e.g., private IP addressesfor application compute instances may be selected by the client withouthaving to consider the possibility that other resources within otherIVNs may have been assigned the same IP addresses, subnets of theclient's choice may be established within the IVN, security rules may beset up by the client for incoming and outgoing traffic with respect tothe IVN, and so on. Isolated virtual networks may be used by the controlplane or administrative components of the VGCS itself for variouspurposes in some embodiments—e.g., in one embodiment, a set ofvirtualized graphics devices may be configured within an IVN. In oneembodiment in which an IVN with a range of private addresses (e.g., IPversion 4 or IP version 6 addresses) is set up on behalf of VGCSclients, a virtual network interface with one or more of the privateaddresses may be established for a graphics session coordinator (GSC) ofthe client. As a result, in such an embodiment, only application computeinstances within the IVN may be able to offload their graphicsprocessing to remote virtualized graphics devices using sessionsestablished via the GSC. Virtual network interfaces may also be referredto as elastic network interfaces in some embodiments. In at least oneembodiment, when a GSC is set up within an IVN, e.g., in response to aprogrammatic request directed to the control plane of the VGCS, the DNS(Domain Name System) configuration information associated with that IVNmay be updated to include one or more IP addresses of the GSC. After theDNS configuration is updated, application compute instances may be ableto obtain the GSC's IP address(es) via DNS requests, and use the IPaddress(es) to submit graphics session requests in such embodiments. Inother embodiments, DNS may not necessarily be used as the mechanism foradvertising GSC network addresses.

Any of a variety of networking protocols may be used for the graphicsrelated traffic in different embodiments. For example, a TransmissionControl Protocol (TCP) connection may be established between theapplication compute instance and one or more remote virtualized graphicsdevices in some embodiments. Other protocols may be used in otherembodiments.

Example System Environment

FIG. 1 illustrates an example system environment for virtualizinggraphics processing in a provider network, according to one embodiment.As shown, system 100 comprises a provider network 101 in which avirtualized graphics and computing service (VGCS) 102 is implemented.The VGCS 102 may include, among other resources, a control plane fleet150, one or more isolated virtual networks (IVNs) such as IVN 130A andIVN 130B established on behalf of respective clients or customers of theVGCS, one or more graphics resource pools 140, and a routing service 160in the depicted embodiment. The VGCS may implement a number ofprogrammatic interfaces in the depicted embodiment, including controlplane programmatic interfaces 170 and data plane programmatic interfaces180. The control plane programmatic interfaces 170 may be used, forexample, to transmit administrative requests from client devices 120 tothe VGCS as indicated by arrow 171, such as requests to establishauto-scaled groups 111 (e.g., auto-scaled groups 111A or 111B) ofvirtualized graphics resources to which graphics sessions 183 may beestablished, to change scaling policies associated with the auto-scaledgroups, to instantiate or launch application compute instances 133, topause or terminate the application compute instances, to view monitoringinformation, and so on. The data plane programmatic interfaces 180 maybe used from client devices to access allocated application computeinstances 133 as indicated by arrow 175, e.g., to initiate/terminatevarious applications, inspect application data, and so on. Any of avariety of interfaces may be used for the control plane and/or dataplane interactions between the clients and the VGCS in differentembodiments, such as web-based consoles, application programminginterfaces (APIs), command line tools, graphical user interfaces and thelike. A client device 120 may, for example, comprise any computingdevice (such as a laptop or desktop computer or host, a tablet computer,a smart phone or the like) from which such interfaces may be utilized orinvoked in various embodiments.

In the depicted embodiment, isolated virtual network (IVN) 130A has beenestablished for a particular customer C1, and comprises at least fourapplication compute instances 133A, 133K and 133L. Each of theapplication compute instances 133 may comprise a respective guestvirtual machine running on a virtualization host 132. For example,virtualization host 132A comprises application compute instances 133A,while virtualization host 132B comprises application compute instances133K and 133L. Similarly, IVN 130B has been established for customer C2,and comprises at least application compute instances 133P and 133Q atvirtualization host 132C. In various embodiments, a configurationrequest to enable the use of an auto-scaled group of remote virtualizedgraphics resources for various application compute instances of an IVNmay be submitted to the VGCS control plane. Such a configuration requestmay also be referred to as an auto-scaled graphics resource grouprequest, or an auto-scaled group request in various embodiments. Anauto-scaled group request may indicate a scaling policy to be appliedfor the graphics resources being requested in at least some embodiments,comprising one or more provisioning rules indicating limits on thenumber and/or type of graphics resources to be deployed as part of theauto-scaled group, as well as other desired characteristics of theauto-scaled group.

In response to receiving such a request or otherwise determining thatautomated scaling of remote virtualized graphics resources is to beenabled on behalf of one or more application compute instances 133 of anIVN 130, one or more computing devices of the VGCS control plane 150 mayestablish a graphics session coordinator 137 within the IVN. Forexample, graphics session coordinator (GSC) 137A associated withauto-scaling group 111A has been established within IVN 130A forapplication compute instances of IVN 130A, and GSC 137B associated withauto-scaling group 111B has been established within IVN 130B in thedepicted embodiment. In some embodiments, a 1:N relationship may existbetween GSCs 137 and auto-scaled groups 111—e.g., a given GSC may beused to establish graphics sessions with multiple auto-scaled groups. Inother embodiments, a 1:1 relationship may exist between GSCs andauto-scaled groups, or an N:1 relationship may exist, in which multipleGSCs may be used to establish sessions with virtualized graphics devicesof a single auto-scaled group. Metadata indicating the particularauto-scaled group(s) 111 associated with a given GSC 137 may be storedat the VGCS control plane in at least some embodiments. In someembodiments, at a customer's request, a plurality of GSCs 137 may beestablished within a given IVN, e.g., with each GSC intended to be usedby a respective subset of the IVN's application compute instances. Inone such embodiment, for example, multiple GSCs may be set up so thatthe graphics-related traffic of a first group of application computeinstance (which may be running a particular type of graphicsapplication) is isolated from the graphics-related traffic of a secondsubset of application compute instances (which may be running adifferent type of graphics application).

A given graphics session coordinator 137, which may be represented by aset of metadata stored within a configuration database of the VGCScontrol plane and may be implemented using one or more computingdevices, may provide an easy-to-access network endpoint enablinggraphics sessions, such as session 183A or 183B, to be established onbehalf of various application compute instances 133 in the depictedembodiment. In at least some embodiments, one or more virtual networkinterfaces may be established for each graphics session coordinator, andone or more network addresses or endpoints assigned to such a virtualnetwork interface may be used to request graphics sessions from theapplication compute instances. Such a virtual network interface may bereferred to as a graphics session coordination interface in at leastsome embodiments, and/or the corresponding endpoints may be referred toas graphics session coordination endpoints. In at least one embodiment,a given graphics session coordination interface may be assigned multipleIP addresses. In some such embodiments, from among multiple IPaddresses, respective IP addresses may be designated for use byrespective groups of application compute instances to establish graphicssessions. In other embodiments, any of the IP addresses may be used byany of the application compute instances for graphics sessions. In oneembodiment, additional IP addresses and/or addition virtual networkinterfaces may be established for graphics session management on behalfof a given set of application compute instances (or a set of othergraphics request generators) over time, e.g., in response to detectionof changing workloads by the VGCS control plane and/or in response torequests from VGCS clients. As mentioned above, in at least someembodiments the graphics session coordinators' network addresses, whichare to be used to request graphics sessions, may be provided to varioustypes of graphics request generators (including application computeinstances) in response to DNS queries. In various embodiments, a GSC 137may provide a secure, flexible mechanism for sharing a collection ofauto-scaled graphics resources such as virtualized graphics devices 143among a set of application compute instances 133. As a result of theestablishment of GSCs, a customer may be able to avoid having to requestvirtualized graphics resources for application compute instances on aper-instance basis in at least some embodiments. Furthermore, in atleast some embodiments, after setting the scaling policy associated witha given auto-scaled group, customers may not have to keep track ofchanging graphics requirements and associated potentially changingbilling costs, thereby considerably simplifying the task of runninggraphics-intensive applications in a cost-effective manner.

A request for a new graphics session 183, e.g., comprising someindication of the remote graphics processing performance needed, or theamount or type of remote virtualized graphics resources needed, may besent from an application compute instance 133 of an IVN 130 to a GSC 137established within the IVN in the depicted embodiment. Such a sessionsetup request may be directed to a private IP address assigned to theGSC 137 in various embodiments; that is, the address may not beaccessible from outside the IVN. The request may be analyzed todetermine whether fulfilling it would lead to a violation of one or morerules indicated in a particular scaling policy associated with the GSC137. For example, if provisioning and/or deploying an additionalvirtualized graphics device 143 would violate a threshold for themaximum permitted number of virtualized graphics devices of theauto-scaling group 111, the request may be rejected in variousembodiments. A message indicating the cause of the rejection may betransmitted to the requesting application compute instance in at leastsome embodiments. If provisioning and/or deploying the resourcesindicated in the session request would not violate any of theprovisioning rules in the applicable scaling policy, in at least someembodiments the request may be approved and one or more remotevirtualized graphics devices 143, such as 143A for session 183A or 143Pfor session 183B may be selected for the session. Connection parameters(such as destination addresses to be used for network packets comprisinggraphics operation requests) for the approved session may be identifiedat the VGCS control plane and transmitted to the requesting applicationcompute instance 133 in the depicted embodiment. In addition, one ormore configuration operations may be initiated or performed at therouting service 160 by the VGCS control plane to enable the graphicsoperation requests to be directed from the application compute instance133 for which the session has been established to the appropriate remotevirtualized graphics device 143 in some embodiments. Similarly, in suchembodiments, configuration operations at the routing service 160 may beperformed to enable packets containing results of the graphicsoperations to be directed from the remote virtualized graphics device tothe appropriate destination (e.g., the requesting application computeinstance and/or some other destination indicated in the sessionrequest). The routing-related configuration operations may include, forexample, generating one or more routing mappings or entries, storingsuch entries in metadata repository 163 and/or propagating the entriesto one or more routers or intermediary devices 164 in the depictedembodiment.

In some embodiments, an auto-scaling manager component 153 of the VGCScontrol plane may be responsible for determining whether sufficientunused resources are available in the graphics resource pool(s) 140 forsetting up requested auto-scaling groups, for identifying the specificresources within the pools 140 that are to be used for a givenauto-scaling group 111 and/or for specific sessions 183, and so on. Inat least one embodiment, the auto-scaling manager 153 may be implementedas a subcomponent of a configuration manager 154, which may for examplebe responsible for other types of configuration operations in additionto auto-scaling of graphics devices. In some embodiments, depending forexample on the provisioning mode indicated in a request to establish anauto-scaling group, an initial number of virtualized graphics devicesmay be instantiated within an auto-scaling group 111 prior to thereceipt of any session requests from the application compute instancesfor which the group is established. In at least some embodiments, atleast some of the application compute instances for which anauto-scaling group 111 is being requested and created may not have beenset up at the time that the auto-scaling group request is submitted—e.g.application compute instance 133A may be instantiated after auto-scalinggroup 111A and/or GSC 137A is set up. A monitoring manager 155 in theVGCS control plane may be responsible in the depicted embodiment forcollecting various performance metrics (such as utilization levels forGPUs, CPUs, memory, networking resources and the like) which can be usedto make auto-scaling decisions and/or to provide insights to clientsregarding the performance of their graphics applications. In at leastone embodiment, metrics indicative of the connectivity betweenapplication compute instances 133 and the remote virtualized graphicsdevices 143 of various sessions 183, as well as the health status of thecompute instances and the virtualized graphics devices themselves, mayalso be collected and/or provided to customers programmatically.

In at least one embodiment, routing metadata including, for example,mappings between a source network address, a source port, an applicationcompute instance, and the remote virtualized graphics device(s) to beused for a given session may be sent to the isolated virtual network andto the graphics resource pool 140, in addition to being sent to therouting service 160. In one embodiment, the mappings may be provided toone or more of the endpoint entities involved in the graphicstraffic—the application compute instance 133 and the remote virtualizedgraphics device(s) 143 to which the application compute instance isconnected during a session. Using the mapping, the application computeinstances and/or the remote virtualized graphics devices may be able toverify that graphics-related network packets or messages that they havereceived are from the appropriate authorized endpoints in variousembodiments, thereby enhancing application security. In one embodiment,for example, prior to performing graphics processing operationsindicated in a received request, a remote virtualized graphics device143 may use the mapping to validate that the request originated at anacceptable or expected application compute instance. In anotherembodiment, before accepting results of graphics processing included ina received message, an application compute instance 133 may use themapping to validate that the message originated at a virtualizedgraphics device to which the corresponding request was directed.

In one embodiment, the VGCS 102 may offer application compute instances133 with varying computational and/or memory resources. In oneembodiment, each of the application compute instances 133 may correspondto one of several instance types. An instance type may be characterizedby its computational resources (e.g., number, type, and configuration ofcentral processing units [CPUs] or CPU cores), memory resources (e.g.,capacity, type, and configuration of local memory), storage resources(e.g., capacity, type, and configuration of locally accessible storage),network resources (e.g., characteristics of its network interface and/ornetwork capabilities), and/or other suitable descriptivecharacteristics. Using instance type selection functionality of the VGCS102, an instance type may be selected for a client, e.g., based (atleast in part) on input from the client. For example, a client maychoose an instance type from a predefined set of instance types. Asanother example, a client may specify the desired resources of aninstance type, and the VGCS control plane may select an instance typebased on such a specification.

In one embodiment, as indicated earlier, the VGCS 102 may offervirtualized graphics devices 143 with varying graphics processingcapabilities. In one embodiment, each of the virtualized graphicsdevices 143 may correspond to one of several virtual GPU classes. Avirtual GPU class may be characterized by its computational resourcesfor graphics processing, memory resources for graphics processing,and/or other suitable descriptive characteristics. In one embodiment,the virtual GPU classes may represent subdivisions of graphicsprocessing capabilities of a physical GPU, such as a full GPU, a halfGPU, a quarter GPU, and so on. The scaling policies associated withauto-scaling groups 111 may indicate the virtual GPU classes to be usedin various embodiments.

In at least one embodiment, the resources of a given virtualization hostand/or a given graphics host may be used in a multi-tenant fashion—e.g.,application compute instances of more than one client may be establishedat a given virtualization host, or virtualized graphics devices for morethan one client may be established at a given graphics host. In otherembodiments, a single-tenant approach may be used with respect to atleast some virtualization hosts and/or at least some graphicshosts—e.g., application compute instances of no more than one client maybe instantiated on a given virtualization host, and virtualized graphicsdevices of no more than one client may be instantiated on a givengraphics host.

FIG. 2 illustrates example components of virtualization hosts andgraphics hosts which may be used for virtualizing graphics processing,according to at least some embodiments. As shown, a virtualization host230 may comprise a set of local hardware devices 239, localvirtualization management components 238, and one or more applicationcompute instances 233 in the depicted embodiment. A graphics host 240may comprise one or more graphic hardware devices 249 (e.g., includinggraphics processing units or GPUs), graphics virtualization managementcomponents 248, and one or more virtualized graphics devices 246 in thedepicted embodiment. The respective virtualization management devices atthe virtualization host and the graphics host may be responsible forhandling interactions between the hardware devices and the virtualdevices implemented at the respective hosts—e.g., the applicationcompute instance(s) and the virtualized graphics device(s). At thevirtualization host, for example, the virtualization managementcomponents may include a hypervisor, a privileged instance of anoperating system, and/or one or more peripheral devices which may beused for handling networking-related virtualization tasks (such astranslations between network addresses assigned to a physical NetworkInterface Card and network addresses of virtual network interfaces) insome embodiments. Analogous virtualization management components may beinstantiated at the graphics host 240 in at least some embodiments.

In the depicted embodiment, an application compute instance 233 (e.g., aguest virtual machine instantiated at virtualization host 230) maycomprise, among other constituent elements, an application program 235,an operating system 237A and a local graphics driver 236. A virtualizedgraphics device 246, which may also be referred to as a graphics virtualmachine, may comprise an operating system 237B and a driver peer 247which communicates with the local graphics driver 236 of the applicationcompute instance 233. A persistent network connection 282 may beestablished (e.g., as part of a procedure to attach the virtualizedgraphics device 246 to the application compute instance 233 between thelocal graphics driver 236 and the driver peer 247 in the depictedembodiment. In some embodiments, for example, TCP may be used for theconnection. Connection parameters 253A and 253B, such as the networkaddresses and ports to be used for the connection at either endpoint,may be determined at the VGCS control plane 250 in response to a requestfor a graphics session, and transmitted to the virtualization hostand/or the graphics host in some embodiments. Graphics processingrequests 276 may be transmitted over the connection 282 from the localgraphics driver 236 to driver peer 247 in the depicted embodiment. Fromthe driver peer 247, corresponding local versions of the graphicprocessing requests may be transmitted to the graphics hardware devices249, and the results 277 obtained from the graphics hardware devices 249may be transmitted back to the virtualization host via connection 282.The local graphics driver 236 may interact with the virtualized graphicsdevice 246 to provide various types of graphics processing operationsfor application program 235 in the depicted embodiment, includingaccelerated two-dimensional graphics processing and/or acceleratedthree-dimensional graphics processing. In one embodiment, the localgraphics driver 236 may implement a graphics application programminginterface (API) such as Direct3D or OpenGL. In the depicted embodiment,the local graphics driver 236 may comprise components running in usermode and/or kernel mode. Additional components (not shown), such as agraphics runtime, may also be used to provide accelerated graphicsprocessing on the application compute instance 233 in some embodiments.

In various embodiments, portions of graphics operation results 277 maybe stored at least temporarily in a client-side cache 251 accessiblefrom (or part of) the local graphics driver. The client-side cache 251may be used, for example, to satisfy some types of graphics operationrequests of the applications 235 locally at the virtualization host 230in the depicted embodiment, e.g., without directing a correspondinggraphics operation request packet to the remote virtualized graphicsdevice. As a result of using locally-cached results, in variousembodiments the overall performance of graphics operations may beimproved and the amount of graphics-related network traffic may bereduced.

The layers of the software/hardware stack at which a network connectionis established and maintained between the virtualization host and thegraphics host may differ in different embodiments. For example, in oneembodiment, a process or thread in the operating system layer 237A ofthe application compute instance may establish a persistent networkconnection with a peer process or thread in the operating system layer237B of the virtualized graphics device 246. In another embodiment, arespective persistent network connection may be established between thevirtualization management components of the virtualization host and thegraphics host(s) for individual application compute instances. In someembodiments, persistent connectivity for graphics-related traffic may beestablished at a layer that lies below the virtualization managementcomponents at each host, and above the respective hardware devices ateach host. In at least one embodiment, instead of transmitting theresults of a requested graphics operation back to the requestingapplication compute instance, a remote virtualized graphics device 246may transmit the results to some other destination indicated in thesession setup request and/or in the graphics operation request.

Graphics Sessions from Outside a Provider Network

As mentioned earlier, application compute instances set up within theVGCS may represent one category of graphics request generators for whichremote virtualized graphics processing may be enabled. FIG. 3illustrates an example system environment in which auto-scaledvirtualized graphics operations may be configured at a provider networkfor graphics request generators external to a provider network,according to at least some embodiments. In system 300, provider network301 may comprise a VGCS 302 which supports auto-scaled remotevirtualized graphics processing for at least three categories ofgraphics request generators in the depicted embodiment: applicationcompute instances such as ACI 333A instantiated within the VGCS itself,graphics request generator hosts such as 305A located withinclient-owned premises such as customer C2's data center 303, andgraphics request generator hosts such as 305B located within otherexternal networks 361 such as a portion of the public Internet. The VGCSmay comprise one or more graphics resource pools 340, each comprisingsome number of remote virtualized graphics devices 343 (e.g., 343A,343B, 343K and 343P) running on graphics hosts 342 (e.g., 342A, 342B and342C). To avoid clutter, the control plane fleet of VGCS 302, which maycomprise a number of components similar to those shown in the VGCScontrol plane fleet 150 of FIG. 1 , is not shown in FIG. 3 .

As in the case of provider network 101 shown in FIG. 1 , providernetwork 301 may also comprise one or more isolated virtual networks(IVNs) such as IVN 330A and IVN 330B. A given IVN 130 may comprise zeroor more application compute instances at a given point in time—e.g.,ACIs 333A, 333K, and 333L may be instantiated at virtualization hosts332A, 332B and 332C respectively within IVN 330A. A graphics sessioncoordinator (GSC) 337A may be established within IVN 330A in thedepicted embodiment to enable graphics sessions such as session 333A tobe set up between application compute instances such as 333A and remotevirtualized graphics devices such as VGD 343A identified from graphicsresource pools 340. During such a session, network packets comprisinggraphics operation requests generated at the application computeinstance may be transmitted to the remote virtualized graphics device asdiscussed earlier, and response packets comprising results of suchoperations may be transmitted to the application compute instance (or aspecified results destination) in the depicted embodiment.

In response to a configuration request, a GSC 337B to be used forgraphics sessions with devices in customer C2's data center may be setup within IVN 330B in the depicted embodiment. A scaling policyindicating various rules to be used to respond to session requests fromdata center 303 and/or to changes in metrics pertaining to graphicsprocessing operations being requested from data center 303 may beindicated for an auto-scaling group of graphics resources associatedwith GSC 337B in the depicted embodiment. An IP address assigned to GSC337B may be accessed from data center 303 using a variety ofconnectivity options in different embodiments—for example, via a secureVPN (virtual private network) connection set up on behalf of customerC2, or using dedicated physical network links sometimes referred to asDirect Connect links, and/or via paths that include portions of thepublic Internet. In a manner similar to that described above withrespect to session requests originating at application computeinstances, graphics session requests may be sent from graphics requestgenerator host 305A located at an external data center 303 to GSC 337B.In response to such a session request, the VGCS control plane maydetermine whether provisioning and/or allocating the virtualizedgraphics device(s) requested for the session would violate the scalingpolicy. If the policy would not be violated, one or more VGDs such asVGD 343B may be selected from a graphics resource pool 340 for thesession 333B in the depicted embodiment. In addition, configurationoperations to enable the flow of graphics operation requests fromgraphics request generator host 305A to the selected VGD(s) and toenable the flow of results of the graphics operations to specifieddestinations may be initiated or performed, e.g., by transmitting andpropagating the appropriate metadata to routing service 360. At therouting service 360, the generated metadata may be stored in repository363 and/or propagated to the routing devices 364 in the depictedembodiment. By establishing the GSC 337B within an IVN, it may bepossible to restrict access to graphics resources to a set of graphicsrequest generators selected by customer C2 in the depicted embodiment,since the IP address(es) assigned to GSC 337B may be chosen by C2.

In at least one embodiment, one or more publicly-accessible graphicssession coordinators such as GSC 338 may be established by the VGCScontrol plane to enable graphics operation requests from externalnetworks to be fulfilled using graphics resource pools 340. A public IPaddress which is advertised outside provider network 301 may be set upfor GSC 338, and a scaling policy may be designated for an auto-scaledgroup set up for external graphics request generators in the depictedembodiment. In response to a request directed to GSC 338 for a graphicssession from a graphics request generator host 305B at an externalnetwork 361, the VGCS control plane may apply the rules of the scalingpolicy designated for the auto-scaled group established for suchsessions. A particular virtualized graphics resource such as VGD 343P atgraphics host 342C may be deployed for the requested session 333C in thedepicted embodiment, and the routing-related configuration operationsrequired for session 333C's traffic may be performed.

In the depicted embodiment, respective local graphics drivers 304A and304B may be installed at the external graphics request generator hosts305A and 305B to enable the use of the VGCS remote virtualized graphicscapabilities. Client-side caches (similar to cache 251 of FIG. 2 ) maybe used in some embodiments to store and potentially re-use results ofgraphics operations at request generator hosts 305, thereby reducing theamount of graphics-related traffic required and improving overallgraphics application performance. In some embodiments, instead ofrequiring local graphics drivers to be installed at the external requestgenerators, the applications running at external request generators maybe required to utilize a set of graphics-related application programminginterfaces (APIs) advertised by or approved by the VGCS. It is notedthat at least in one embodiment, an auto-scaling group with specificrules may not explicitly be established for supporting graphics sessionswith external graphics request generators such as host 305B. Instead, apool of graphics resources may be set up for such externally-requestedgraphics sessions, and resources from that pool may be allocated inresponse to session requests until the resources are exhausted. Whengraphics sessions are terminated, the corresponding resources may bereturned to the pool, and new session establishment may be resumed.

Example Programmatic Interactions

FIG. 4 illustrates example programmatic interactions which may be usedto establish or modify an auto-scaled virtualized graphics resourcegroup, according to at least some embodiments. As shown, a VGCS client410 may submit an auto-scaled graphics resource group setup request 401to the VGCS control plane 490 via a programmatic interface 402 in thedepicted embodiment. A variety of programmatic interfaces such asweb-based consoles, APIs, graphical user interfaces, and/or command-linetools may be used in various embodiments. In the depicted embodiment,the setup request 401 may comprise, among other elements, a requestertypes list 450, one or more identifier(s) 452 of respective isolatedvirtual networks, a scaling policy 471 and a monitoring specification408. The requester types list 450 may indicate whether the auto-scaledgroup of graphics resources is intended to be utilized for graphicsrequest generators within IVN(s) with identifiers 452 whether thegraphics requests may be generated at client-premises as discussed inthe context of FIG. 3 , whether the graphics requests may be generatedat external public networks, or whether some combination of such typesof requesters are to be supported.

The scaling policy 471 may indicate one or more provisioning modes 473(such as exclusive provisioning or best-effort provisioning), a graphicsdevice category list 475, minimum/maximum device counts 477 for zero ormore of the categories indicated in list 475, and add/remove devicerules 479 for zero or more of the categories indicated in list 475 inthe depicted embodiment. If an exclusive provisioning mode is indicatedin the scaling policy, the VGCS control plane may reserve a poolcomprising the requested numbers of devices of various types indicatedin category list 475 for exclusive use by the graphics requestgenerators indicated in requester types list 450 in the depictedembodiment. As a result, as long as the maximum number of remotevirtualized graphics devices of a given category allocated to thespecified types of graphics request generators is not exceeded, requestsfor sessions requiring additional remote VGDs may succeed. If abest-effort provisioning mode is indicated, in various embodiments theVGCS may not always be able to fulfill a session request even if thecorresponding maximum device counts have not yet been exceeded—e.g.,there may a small probability that a session request may be rejected dueto unavailability of graphics resources in such circumstances, althoughin most cases the VGCS would be able to fulfill such session requests.In the best-effort provisioning mode, in effect the client may provide ahint regarding the likely range of the number of graphics devices thatmay be needed, without requesting exclusive reservations in someembodiments. In at least some embodiments, a per-graphics-device billingrate may differ for exclusive provisioning mode from the correspondingbilling rate for best-effort provisioning mode.

The add/remove device rules 479 may indicate the logic to be used todecide whether additional virtualized graphics devices are to be addedto or deployed for a given session, or whether currently-allocatedvirtualized graphics devices are to be removed/un-deployed from a givensession in the depicted embodiment. The rules for adding or removingdevices may be expressed in terms of monitored metrics in at least someembodiments. Monitoring specification 408 may indicate the kinds ofmetrics (e.g., GPU utilization, CPU utilization, and the like) which areto be collected for enforcing the add/remove device rules 479. In oneembodiment, for example, the add/remove device rules 479 may indicatethat if the average GPU utilization for the set of remote virtualizeddevices currently deployed for a session exceeds X % for some timeperiod T1, an additional virtualized graphics device with G GPUs shouldbe deployed. Similarly, with respect to removing devices, in oneembodiment a rule 479 may indicate that if the average GPU utilizationfor the set of remote virtualized devices currently deployed for asession remains below Y % for some time period T2, and if the number ofremote virtualized devices of the session exceeds one, one of the remotevirtualized devices should be un-deployed.

A component of the VGCS control plane 490 such as an auto-scalingmanager 493 or a configuration manager may determine whether thegraphics resource pools of the VGCS and/or associated networkingcomponents have sufficient capacity to establish the requestedauto-scaled group in the depicted embodiment. If sufficient capacity isavailable, one or more entries may be added to a configuration database492 to indicate the creation of the requested auto-scaled group and acorresponding graphics session coordinator. A virtual network interfacemay be established within a specified IVN for the graphics sessioncoordinator in at least some embodiments, with one or more IP addressesof the virtual network interface being set up to receive sessionrequests. A resource group setup acknowledgement 420 may be sent to theclient 410 in some embodiments, comprising an identifier 421 of theauto-scaled resource group and/or information 422 (such as one or moreIP addresses) pertaining to the graphics session coordinator to be usedfor session requests. Subsequently, in at least some embodiments, theclient 410 may submit requests 431 to modify the resource group (e.g.,by adding one or more graphics session coordinators, changing thetypes/numbers of VGDs that can be used, and so on). The VGD controlplane 490 may make the requested changes if possible, and respond with aresource group status message 432 in the depicted embodiment. Otherprogrammatic interactions regarding auto-scaled groups of graphicsresources may also be supported in at least some embodiments, such asrequests to display the status of an auto-scaled group (e.g., the countof virtualized graphics devices currently in use, the number of activesessions underway, the history of sessions over some time period,performance statistics, health state, and the like) and so on.

FIG. 5 illustrates example programmatic interactions associated withestablishing sessions for virtualized graphics operations, according toat least some embodiments. As shown, two application compute instances510A and 510B may submit respective graphic session setup requests 501Aand 501B to an address associated with graphics session coordinator 570via programmatic interfaces 502. Each of the session setup requests mayindicate, for example, a respective performance target 502 (e.g., target502A or 502B) and/or results destination information 552 (e.g., 552A or552B).

The performance target 502 for a session may be expressed, for example,in terms of the number of virtualized graphics devices of one or morecategories in some embodiments. For example, a VGCS may support threecategories of remote virtualized graphics devices, labeled “small”,“medium” and “large”, which differ from one another in their graphicsoperation performance capability limits, in one embodiment, and aperformance target 502 may indicate the number of devices of one or moretypes that are being requested for the session. In another embodiment,the performance targets 502 may be expressed in terms of GPUs of aspecified type, or in terms of throughput or response time goals withrespect to a set of graphics APIs, and the VGCS control plane 590 maytranslate such targets into the appropriate set of remote virtualizedgraphics devices of one or more categories. In the depicted embodiment,the results destination information 552 may indicate whether the packetscontaining results of requested graphics operations are to be sent backto the application compute instance from which the requests were sent,or whether the packets are to be sent to some other specifieddestination (such as a client device).

In some embodiments, the auto-scaling manager 593 of the VGCS controlplane may determine whether the requested resources can be deployedwithout violating the scaling policy in effect. The scaling policyrelevant for a given session request may be identified, for example,based on the identity or source address of the application computeinstance 510, the network address of the graphics session coordinator570 to which the session setup request was sent, or some combination ofsuch factors in different embodiments. If the scaling policy would notbe violated and there are sufficient resources available in a graphicsresource pool designated for the auto-scaled group associated with thegraphics session coordinator 570 and the application compute instance510A, one or more virtualized graphics devices may be instantiated(unless pre-instantiated virtualized graphics devices are available, asmay be the case if the exclusive provisioning mode is being employed)and deployed for the session in the depicted embodiment. Routing-relatedconfiguration operations may be initiated by the VGCS control plane asdiscussed earlier to ensure that packets containing graphics operationrequests can be directed from the application compute instance 510A tothe deployed virtualized graphics devices, and that the packetscontaining results of the operations can be directed to the specifiedresults destination indicated in the session setup request 501A. In atleast one embodiment, one or more entries pertaining to the approvedsession may be stored in a configuration database 592 at the VGCScontrol plane.

A session approval response 505A comprising connection parameters (e.g.,a destination IP address to be used for packets containing graphicsoperation requests) may be generated and sent to application computeinstance 510A in the depicted embodiment. The connection parameters maybe used by the application compute instance 510A to establish persistentnetwork connections to be used for graphics operation requests and/orresponses in various embodiments during the session. Later, e.g., afterthe graphics-related application being run at application computeinstance has completed its graphics operations, a request to terminatethe session may be transmitted to the VGCS control plane in the depictedembodiment. In response, the graphics resources that were being used forthe session may be freed, so that they may be re-used for some othersession if needed. In at least one embodiment, when a session isterminated, the contents of at least a portion of the memory or storageused by the remote virtualized graphics device may be scrubbed oroverwritten to ensure that graphics state information of the applicationthat was being executed during the concluded session cannot be accessedduring a subsequent session.

The VGCS control plane 590 may determine that session request 501B fromapplication compute instance 510B cannot be fulfilled without violatingthe applicable scaling rule in the depicted embodiment (e.g., becausethe maximum permitted number of virtualized graphics devices of therequested type(s) have already been deployed). Consequently, a sessionrejected response 509 comprising an error message 512 indicating thereason for the rejection may be sent to the application compute instance510B. It is noted that similar interactions to those shown in FIG. 5 mayoccur between other types of graphics request generators and the VGCScontrol plane 590 in various embodiments—e.g., session requests may begenerated from hosts located outside the provider network as discussedin the context of FIG. 3 .

Addressing Schemes

As mentioned earlier, a number of alternative approaches regarding thedestination addresses to be used for packets containing graphicsoperation requests may be taken in different embodiments. FIG. 6 a andFIG. 6 b illustrate respective examples of addressing schemes which maybe used for packets comprising graphics operation requests, according toat least some embodiments. In the embodiment depicted in FIG. 6 a , agraphics session coordinator 610A has an IP address 620A, and a remotevirtualized graphics device 630A has an IP address 620B. A packetcomprising a session setup request is sent from application computeinstance 605A with IP address 620A as its destination address, asindicated by the arrow labeled “1”. The session may be approved by thegraphics session coordinator, as indicated by the arrow labeled “2”. Thesession approval message may indicate connection parameters to be usedfor the session in the depicted embodiment, including for example the IPaddress 620B of the remote VGD 630A. Subsequently, as indicated by thearrow labeled “3”, packets containing graphics operation requests mayindicate the address 620B as their destination. As shown, in theembodiment depicted in FIG. 6 a , the graphics session coordinator mayact as a distributor or provider of the destination addresses of remotevirtualized graphics devices, and those addresses may be used during thegraphics sessions by the request generators such as application computeinstance 605A.

In the embodiment depicted in FIG. 6 b , a session request may also bedirected to the IP address 620C of the graphics session coordinator 610Bfrom application compute instance 605B, as indicated by the arrowlabeled “1”. In the session approval response message indicated by thearrow labeled “2”, the connection parameters provided may indicate thatthe address 620C of the graphics session coordinator 610B is to be usedfor packets containing graphics operation requests. Subsequently, theapplication compute instance 605B may generate packets with adestination address 620C for requesting graphics operations, asindicated by label “3”. The routing service and/or other networkingintermediaries may comprise address translators 650 which transform thepackets containing graphics requests to indicate IP address 620D of thevirtualized graphics device to be used for the session as theirdestination, as indicated by the label “4” in the embodiment depicted inFIG. 6 b . As shown in FIG. 6 b , the IP address 620C of the sessioncoordinator may be used as the destination address for packetsassociated with at least two types of operations in someembodiments—session establishment, and graphics operations during asession. In effect, details such as the IP addresses of the remotevirtualized graphics devices may not be provided to the applicationcompute instances or other graphics request generators in suchembodiments, and the required address translations or transformationsfor routing the graphics operation requests may be performedautomatically by the VGCS and/or the routing service.

Intra-Session Auto-Scaling Operations

As mentioned earlier, auto-scaling may be implemented at severaldifferent levels in some embodiments, including session-initiation leveland intra-session level. At the session-initiation level, decisions maybe made in accordance with a scaling policy of an auto-scaled resourcegroup, to deploy additional graphics resources for new sessions that arebeing requested. At the intra-session level, decisions regardingenabling access to additional graphics resources from a particulargraphics request generator during an ongoing session may be made in atleast some embodiments. FIG. 7 a and FIG. 7 b illustrate respectiveexamples of intra-session auto-scaling changes, according to at leastsome embodiments.

In the embodiment depicted in FIG. 7 a , in an initial configuration740A for a session requested by a graphics request generator 705A (e.g.,an application compute instance), a single remote virtualized graphicsdevice 730A may be deployed. Various performance metrics associated withthe graphics operations being performed during the session may bemonitored in the depicted embodiment, such as utilization metrics of theremote VGD 730A or the network paths being used for the graphics-relatedtraffic, response time metrics and/or throughput metrics for varioustypes of graphics operations being requested, and so on. The VGCScontrol plane may determine, e.g., based at least in part on the metricsand at least in part on unused capacity of the graphics resource pool(s)associated with the session, that an additional remote VGD 730B shouldbe deployed for the session. Accordingly, connection parameters may betransmitted to graphics request generator 705A to enable theestablishment of a persistent connection with remote VGD 730B in thedepicted embodiment, resulting in modified configuration 740B. Inaddition, and routing-related configuration changes may be made toenable request packets to flow to VGD 730B from graphics requestgenerator 705A and response packets to flow from VGD 730B to one or moregraphics result destinations specified for the session in the embodimentdepicted in FIG. 7 a . The local graphics driver at the graphics requestgenerator 705 may decide which subset of graphics requests is to be sentto each of the two VGDs 730A and 730B in the depicted embodiment.

In some cases, a given virtualized graphics device may be shared amongseveral graphics request generators based on analysis of performancemetrics. In the embodiment depicted in FIG. 7 b , remote VGDs 730C and730D are deployed for respective graphics sessions set up on behalf ofgraphics request generators 705C and 705D in initial configuration 740C.Based on data collected via monitoring tools or agents, the VGCS controlplane may determine that VGD 730D is under-utilized, while VGD 730C isover-utilized in the depicted embodiment. A determination may be madethat some of the unused capacity of VGD 730D should be made available tographics request generator 705C. Connection parameters to enable VGD730C to be utilized for graphics operation requests may be transmittedto request generator 705C, and the appropriate routing changes may beinitiated, resulting in a modified configuration 740D in the depictedembodiment. Using the types of intra-session auto-scaling operationsillustrated in FIGS. 7 a and 7 b , as well as the session-initiationlevel auto-scaling operations discussed earlier, the VGCS may be able tosatisfy diverse dynamically-changing requirements for graphicsoperations of client applications in various embodiments.

Graphics Resource Pools

As mentioned earlier, several different provisioning modes forauto-scaled virtualized graphics resources may be supported in someembodiments, including for example exclusive provisioning andbest-effort provisioning. In at least one embodiment, respective poolsof graphics resources may be established for the different provisioningmodes. Furthermore, in some embodiments in which the VGCS is implementedat a geographically distributed provider network comprising a pluralityof data centers, the physical locations of the hardware used for thevirtualized graphics resources (relative to the locations from which thegraphics operations requests are expected) may be taken into accountwhen sessions are set up, e.g., so as to reduce transmission times forpackets containing graphics operation requests or results of suchoperations. Multiple geographically distributed pools of graphicsresources may be set up in various embodiments for supporting thedesired performance levels and/or the different provisioning modes.

FIG. 8 illustrates example categories of graphics resource pools whichmay be established at a provider network, according to at least someembodiments. In the depicted embodiment, provider network 802 comprisesresources distributed among various geographical regions, such as region804A and 804B. Within a given region 804, one or more availabilitycontainers 806 may be established, such as availability containers 806Aand 806B in region 804A, and availability containers 806C and 806D inregion 804B. Availability containers may also be referred to as“availability zones” in some embodiments. An availability container maycomprise portions or all of one or more distinct locations or datacenters, engineered in such a way (e.g., with independent infrastructurecomponents such as power-related equipment, cooling equipment, orphysical security components) that the resources in a given availabilitycontainer are insulated from failures in other availability containers.A failure in one availability container may not be expected to result ina failure in any other availability container; thus, the availabilityprofile of a given resource is intended to be independent of theavailability profile of resources in a different availability container.Various types of services and/or applications may therefore be protectedfrom failures at a single location by launching multiple applicationinstances or resource instances in respective availability containers,or distributing the nodes of a given service across multipleavailability containers.

In the embodiment depicted in FIG. 8 , two types of graphics resourcepools may be created: reserved pools for the exclusive use of graphicssessions of one customer, and shared pools which may be used forgraphics sessions of multiple customers. Individual ones of the pools ofeither type may comprise, for example, respective sets of physicaland/or virtual resources, such as graphics hosts comprising GPUs,pre-configured virtualized graphics devices instantiated on such hosts,and the like. In FIG. 8 , to avoid clutter, only virtualized graphicsdevices (which may be pre-configured or may be instantiated after asession request has been accepted) are shown, and the correspondingphysical resources such as graphics hosts are not shown. For example, inavailability container 806A, reserved pool 807A comprising some numberof virtualized graphics devices such as 807A running on a set ofgraphics hosts may be established for customer C1 and reserved pool 807Bcomprising VGD 843J may be established for customer C3. Similarly, inavailability container 806B, reserved pool 807B comprising VGD 843G maybe set up for customer C2. Customer C4 may have two reserved pools ofgraphics resources allocated in the depicted embodiment, pool 807D inavailability container 806C and pool 807E in availability container806D. Shared pools of graphics resources may be established in each ofthe availability containers in the depicted embodiment, such as sharedpool 810A comprising VGD 843A in availability container 806A, sharedpool 810B comprising VGD 843B in availability container 806B, sharedpool 806C comprising VGD 843P in availability container 806C and sharedpool 806D comprising VGD 843Q in availability container 806D.

The reserved pools 807 may be established in response to respectiverequests for auto-scaled resource groups in exclusive provisioning modein the depicted embodiment. The specific availability container withinwhich a reserved pool is set up may be selected based at least in parton a preferred-location parameter of the auto-scaled group setuprequest, or based on the location of the graphics request generators.For example, if most of the graphics operation requests directed to aparticular auto-scaled group are expected from a particular geographicalregion (whether the requesters are application compute instances insidethe provider network, or hosts external to the provider network), one ormore availability containers located in or near that region may be used.Similarly, the particular shared pool 806 from which VGDs are allocatedor deployed for a given session request may be selected based at leastin part on geographical proximity to the graphics request generator forwhich the session is to be established in some embodiments.

Methods for Auto-Scaled Remote Virtualized Graphics Operations

FIG. 9 is a flow diagram illustrating aspects of operations that may beperformed to support automated scaling of virtualized graphicsresources, according to at least some embodiments. As shown in element901, a determination may be made, e.g., at a control plane component ofa VGCS at a provider network, that a group of auto-scaled remotevirtualized graphics resources or devices is to be set up for use by oneor more application compute instances or other graphics requestgenerators. Such a determination may be made, for example, in responseto receiving an auto-scaled resource group setup request similar to thatdiscussed in the context of FIG. 4 in some embodiments.

One or more pools of graphics resources from which VGDs are to bedeployed for the sessions initiated by the graphics request generatorsmay be identified and/or populated (element 904) in the depictedembodiment. For example, if exclusive provisioning is to be used, a newpool comprising the maximum number of VGDs indicated in the scalingpolicy may be established, and if best-effort provisioning is indicated,a shared pool of VGDs may be selected (or created, if such a pool hasnot been established yet in the appropriate availability container orgeographical region). The physical proximity of the pool to theprospective graphics resource requesters may be among the factorsconsidered in selecting the particular pool in at least someembodiments.

A graphics session coordinator (GSC) may be established for theauto-scaled group in the depicted embodiment (element 907). The GSC maycomprise a virtual network interface with one or more network addressesaccessible to the prospective graphics resource requesters for which theauto-scaled group is being established. For example, a private IPaddress may be identified for the virtual network interface within anisolated virtual network comprising a set of application computeinstances which are to use the graphics resources in some embodiments.In other embodiments, a public IP address accessible from externalnetworks such as the Internet may be used. The address(es) to be used tocommunicate with the GSC may be transmitted to the client requesting theauto-scaled group, and/or provided to the graphics request generators insome embodiments.

A determination may be made at the VGCS control plane that a request fora graphics session has been submitted by a graphics request generator,e.g., using one or more packets with the GSC's network address indicatedas the destination address (element 910). In some embodiments, thesession request may indicate resource requirements, such as the numberof virtualized graphics devices of one or more types to be used duringthe graphics session. In at least one embodiment, a default number(e.g., one) of remote virtualized graphics may be assumed as therequirement if no specific requirement is indicated in the sessionrequest. In one embodiment, the session request may indicate aperformance goal (e.g., the number of graphics operations of a certaintype which are to be performed per second), and the VGCS control planemay translate the performance requirements into the number of graphicsdevices of one or more types which are to be deployed.

The VGCS control plane may make a determination as to whether, in viewof the scaling policy associated with the auto-scaled group set up forthe graphics request generator, sufficient resources are available forthe requested session. If the resources requested can be deployedwithout violating the scaling policy and the appropriate pools containenough resources for the session, as determined in element 913, one ormore remote virtualized graphics devices that meet the requirements ofthe session may be identified from the appropriate pools (element 919).Configuration operations which enable packets containing graphicsoperation requests from the request generator to be transmitted to theremote virtualized graphics device(s) may be initiated, e.g., bygenerating the appropriate routing metadata or mappings at the VGCScontrol plane and transmitting the metadata to a routing service.Similarly, configuration operations that enable packets containing theresults of the graphics operations to be directed to a specified resultdestination for the session may be performed in the depicted embodiment.

Connection parameters for the session may be transmitted to the graphicsrequest generator in the depicted embodiment (element 922). The requestgenerator may start sending graphics operation requests to the VGD(s),and the VGD(s) in turn may start performing the requested operations andsending responses to the results destinations. The VGCS control planemay collect monitoring data (e.g., utilization levels, response timesfor graphics operations, etc.) pertaining to sessions and graphicsresource pools in the depicted embodiment (element 925). Based on themonitored data, the scaling policy and/or resource modification requestsfrom the client, graphics devices may be dynamically added to or removedfrom the graphics session(s) (element 928), and the correspondingrouting configuration changes may be performed when such devices areadded or removed.

If, in operations corresponding to element 913, a determination is madethat the requested session requires resources whose deployment wouldviolate the scaling policy, the session request may be rejected in thedepicted embodiment (element 916), and an optional error message may betransmitted to the session request source indicating that the scalingpolicy in effect would be violated if the session were established.

In at least some embodiments, a graphics session coordinator may be setup as a conduit or mechanism for requesting graphics sessions ingeneral, and may not necessarily be tied to a particular auto-scaledresource group or a scaling policy. For example, in one embodiment, agraphics session coordinator may be established in response to adetermination that remote virtualized graphics processing is to beenabled for a set of graphics request generators, without any specificauto-scaling requirements. Such a general-purpose graphics sessioncoordinator may be used in various embodiments to set up and tear downgraphics sessions in a manner similar to that described herein forsessions established with respect to auto-scaled graphics resourcegroups. Before approving a new session or adding resources to anexisting session, such a general-purpose graphics session coordinatormay check whether the VGCS as a whole has enough unused graphicsresources in some embodiments.

It is noted that in various embodiments, some of the operations shown inFIG. 9 may be implemented in a different order than that shown in thefigure, or may be performed in parallel rather than sequentially.Additionally, some of the operations shown in FIG. 9 may not be requiredin one or more implementations.

Use Cases

The techniques described above, of supporting automated scaling ofremote virtualized graphics processing using configurable graphicssession coordinators, may be useful in a variety of scenarios. A widevariety of applications may be able to benefit from advanced graphicsprocessing capabilities, such as applications in the domains of gamestreaming, rendering, financial modeling, engineering design, scientificvisualization/simulation, and the like. Executing such applications onconventional CPUs may not be efficient, especially for large data sets.Using remote-attached virtualized graphics devices may be a moresuitable approach for at least some such applications. However, for somesuch applications, it may not always be possible to predict the amountof graphics processing in advance. The auto-scaling and graphics sessionmanagement techniques outlined herein may enable customers of avirtualized graphics and computing service to deal with varying graphicsworkloads with relatively little effort, leaving most of the work ofselecting the appropriate graphics resources as the workloads change tothe service while ensuring that approved scaling policies are enforced.

Illustrative Computer System

In at least some embodiments, a server that implements one or more ofthe techniques described above for managing traffic associated withvirtualized graphics processing, including a configuration manager, anauto-scaling manager, routers, and various other control plane and dataplane entities of a virtualized graphics and computing service or arouting service, may include a general-purpose computer system thatincludes or is configured to access one or more computer-accessiblemedia. FIG. 10 illustrates such a general-purpose computing device 9000.In the illustrated embodiment, computing device 9000 includes one ormore processors 9010 coupled to a system memory 9020 (which may compriseboth non-volatile and volatile memory modules) via an input/output (I/O)interface 9030. Computing device 9000 further includes a networkinterface 9040 coupled to I/O interface 9030.

In various embodiments, computing device 9000 may be a uniprocessorsystem including one processor 9010, or a multiprocessor systemincluding several processors 9010 (e.g., two, four, eight, or anothersuitable number). Processors 9010 may be any suitable processors capableof executing instructions. For example, in various embodiments,processors 9010 may be general-purpose or embedded processorsimplementing any of a variety of instruction set architectures (ISAs),such as the x86, PowerPC, SPARC, or MIPS ISAs, or any other suitableISA. In multiprocessor systems, each of processors 9010 may commonly,but not necessarily, implement the same ISA. In some implementations,graphics processing units (GPUs) may be used instead of, or in additionto, conventional processors.

System memory 9020 may be configured to store instructions and dataaccessible by processor(s) 9010. In at least some embodiments, thesystem memory 9020 may comprise both volatile and non-volatile portions;in other embodiments, only volatile memory may be used. In variousembodiments, the volatile portion of system memory 9020 may beimplemented using any suitable memory technology, such as static randomaccess memory (SRAM), synchronous dynamic RAM or any other type ofmemory. For the non-volatile portion of system memory (which maycomprise one or more NVDIMMs, for example), in some embodimentsflash-based memory devices, including NAND-flash devices, may be used.In at least some embodiments, the non-volatile portion of the systemmemory may include a power source, such as a supercapacitor or otherpower storage device (e.g., a battery). In various embodiments,memristor based resistive random access memory (ReRAM),three-dimensional NAND technologies, Ferroelectric RAM, magnetoresistiveRAM (MRAM), or any of various types of phase change memory (PCM) may beused at least for the non-volatile portion of system memory. In theillustrated embodiment, program instructions and data implementing oneor more desired functions, such as those methods, techniques, and datadescribed above, are shown stored within system memory 9020 as code 9025and data 9026.

In one embodiment, I/O interface 9030 may be configured to coordinateI/O traffic between processor 9010, system memory 9020, networkinterface 9040 or other peripheral interfaces such as various types ofpersistent and/or volatile storage devices. In some embodiments, I/Ointerface 9030 may perform any necessary protocol, timing or other datatransformations to convert data signals from one component (e.g., systemmemory 9020) into a format suitable for use by another component (e.g.,processor 9010). In some embodiments, I/O interface 9030 may includesupport for devices attached through various types of peripheral buses,such as a Low Pin Count (LPC) bus, a variant of the Peripheral ComponentInterconnect (PCI) bus standard or the Universal Serial Bus (USB)standard, for example. In some embodiments, the function of I/Ointerface 9030 may be split into two or more separate components, suchas a north bridge and a south bridge, for example. Also, in someembodiments some or all of the functionality of I/O interface 9030, suchas an interface to system memory 9020, may be incorporated directly intoprocessor 9010.

Network interface 9040 may be configured to allow data to be exchangedbetween computing device 9000 and other devices 9060 attached to anetwork or networks 9050, such as other computer systems or devices asillustrated in FIG. 1 through FIG. 9 , for example. In variousembodiments, network interface 9040 may support communication via anysuitable wired or wireless general data networks, such as types ofEthernet network, for example. Additionally, network interface 9040 maysupport communication via telecommunications/telephony networks such asanalog voice networks or digital fiber communications networks, viastorage area networks such as Fibre Channel SANs, or via any othersuitable type of network and/or protocol.

In some embodiments, system memory 9020 may be one embodiment of acomputer-accessible medium configured to store program instructions anddata as described above for FIG. 1 through FIG. 9 for implementingembodiments of the corresponding methods and apparatus. However, inother embodiments, program instructions and/or data may be received,sent or stored upon different types of computer-accessible media.Generally speaking, a computer-accessible medium may includenon-transitory storage media or memory media such as magnetic or opticalmedia, e.g., disk or DVD/CD coupled to computing device 9000 via I/Ointerface 9030. A non-transitory computer-accessible storage medium mayalso include any volatile or non-volatile media such as RAM (e.g. SDRAM,DDR SDRAM, RDRAM, SRAM, etc.), ROM, etc., that may be included in someembodiments of computing device 9000 as system memory 9020 or anothertype of memory. Further, a computer-accessible medium may includetransmission media or signals such as electrical, electromagnetic, ordigital signals, conveyed via a communication medium such as a networkand/or a wireless link, such as may be implemented via network interface9040. Portions or all of multiple computing devices such as thatillustrated in FIG. 10 may be used to implement the describedfunctionality in various embodiments; for example, software componentsrunning on a variety of different devices and servers may collaborate toprovide the functionality. In some embodiments, portions of thedescribed functionality may be implemented using storage devices,network devices, or special-purpose computer systems, in addition to orinstead of being implemented using general-purpose computer systems. Theterm “computing device”, as used herein, refers to at least all thesetypes of devices, and is not limited to these types of devices.

CONCLUSION

Various embodiments may further include receiving, sending or storinginstructions and/or data implemented in accordance with the foregoingdescription upon a computer-accessible medium. Generally speaking, acomputer-accessible medium may include storage media or memory mediasuch as magnetic or optical media, e.g., disk or DVD/CD-ROM, volatile ornon-volatile media such as RAM (e.g. SDRAM, DDR, RDRAM, SRAM, etc.),ROM, etc., as well as transmission media or signals such as electrical,electromagnetic, or digital signals, conveyed via a communication mediumsuch as network and/or a wireless link.

The various methods as illustrated in the Figures and described hereinrepresent exemplary embodiments of methods. The methods may beimplemented in software, hardware, or a combination thereof. The orderof method may be changed, and various elements may be added, reordered,combined, omitted, modified, etc.

Various modifications and changes may be made as would be obvious to aperson skilled in the art having the benefit of this disclosure. It isintended to embrace all such modifications and changes and, accordingly,the above description to be regarded in an illustrative rather than arestrictive sense.

What is claimed is:
 1. A method, comprising: performing, at one or morecomputing devices implementing a virtualized graphics service:obtaining, from a client of the virtualized graphics service via aprogrammatic interface of the virtualized graphics service, a request toestablish an auto-scaled group to process requests from a graphicsrequest source of the client, the request indicating a client-specifiedscaling policy comprising one or more provisioning rules for adding orremoving remote graphics processing devices to or from the auto-scaledgroup; identifying, based at least in part on the client-specifiedscaling policy, one or more remote graphics processing devices of anetwork-accessible graphics computing service to process requests fromthe graphics request source of the client as part of the auto-scaledgroup; causing one or more network connections to be established betweenthe graphics request source and a first remote graphics processingdevice of the one or more remote graphics processing devices; andtransmitting, from the first remote graphics processing device, a resultof a graphics operation requested by the graphics request source via theone or more network connections.
 2. The method as recited in claim 1,wherein the client-specified scaling policy indicates that an exclusiveprovisioning mode is to be employed to assign remote graphics processingdevices, the method further comprising performing, at the one or morecomputing devices: reserving, in accordance with the exclusiveprovisioning mode, the one or more remote graphics processing devicesfor exclusive use by the graphics request source.
 3. The method asrecited in claim 1, wherein the client-specified scaling policyindicates that a non-exclusive provisioning mode is to be employed toassign remote graphics processing devices, the method further comprisingperforming, at the one or more computing devices: selecting, inaccordance with the non-exclusive provisioning mode, the one or moreremote graphics processing devices from a pool of remote graphicsprocessing devices which is shared among a plurality of graphics requestsources.
 4. The method as recited in claim 1, wherein theclient-specified scaling policy indicates a particular category of aplurality of categories of remote graphics processing devices of thegraphics computing service, wherein the particular category differs fromanother category of the plurality of categories in a performancecapability, and wherein at least one remote graphics processing deviceof the one or more remote graphics processing devices belongs to theparticular category.
 5. The method as recited in claim 1, wherein theclient-specified scaling policy indicates one or more rules to be usedto modify a number of remote graphics processing devices assigned to thefirst graphics request source, the method further comprising performing,by the one or more computing devices: assigning, in accordance with theone or more rules, an additional remote graphics processing device tothe first graphics request source.
 6. The method as recited in claim 1,further comprising performing, at the one or more computing devices:causing a transformed version of a first request packet originating atthe graphics request source to be delivered to a particular remotegraphics processing device, wherein the destination address of the firstrequest packet differs from an address of the particular remote graphicsprocessing device, and wherein the destination address of thetransformed version is the address of the particular remote processingdevice.
 7. The method as recited in claim 1, wherein the first remotegraphics processing device comprises a virtualized device instantiatedat a host comprising one or more graphics hardware devices including atleast one graphics processing unit (GPU).
 8. The method as recited inclaim 1, wherein the first remote graphics processing device isconfigured to utilize at least one graphics processing unit (GPU) toperform operations requested from the graphics request source.
 9. Asystem, comprising: one or more computing devices; wherein the one ormore computing devices include instructions that upon execution on oracross one or more processors cause the one or more computing devices toimplement a virtualized computing service configured to: obtain, from aclient of the virtualized graphics service via a programmatic interfaceof the virtualized graphics service, a request to establish anauto-scaled group to process requests from a graphics request source ofthe client, the request indicating a client-specified scaling policycomprising one or more provisioning rules for adding or removing remotegraphics processing devices to or from the auto-scaled group; identify,based at least in part on the client-specified scaling policy, one ormore remote graphics processing devices of a network-accessible graphicscomputing service to process requests from a graphics request source ofthe client as part of the auto-scaled group; cause one or more networkconnections to be established between the graphics request source and afirst remote graphics processing device of the one or more remotegraphics processing devices; and transmit, from the first remotegraphics processing device, a result of a graphics operation requestedby the graphics request source via the one or more network connections.10. The system as recited in claim 9, wherein the client-specifiedscaling policy indicates that an exclusive provisioning mode is to beemployed to assign remote graphics processing devices, and wherein theone or more computing devices include further instructions that uponexecution on or across the one or more processors further cause the oneor more computing devices to: reserve, in accordance with the exclusiveprovisioning mode, the one or more remote graphics processing devicesfor exclusive use by the graphics request source.
 11. The system asrecited in claim 9, wherein the client-specified scaling policyindicates that a non-exclusive provisioning mode is to be employed toassign remote graphics processing devices, and wherein the one or morecomputing devices include further instructions that upon execution on oracross the one or more processors further cause the one or morecomputing devices to: select, in accordance with the non-exclusiveprovisioning mode, the one or more remote graphics processing devicesfrom a pool of remote graphics processing devices which is shared amonga plurality of graphics request sources.
 12. The system as recited inclaim 9, wherein the client-specified scaling policy indicates aparticular category of a plurality of categories of remote graphicsprocessing devices of the graphics computing service, wherein theparticular category differs from another category of the plurality ofcategories in a performance capability, and wherein at least one remotegraphics processing device of the one or more remote graphics processingdevices belongs to the particular category.
 13. The system as recited inclaim 9, wherein the client-specified scaling policy indicates one ormore rules to be used to modify a number of remote graphics processingdevices assigned to the first graphics request source, and wherein theone or more computing devices include further instructions that uponexecution on or across the one or more processors further cause the oneor more computing devices to: reduce, in accordance with the one or morerules, a count of remote graphics processing devices assigned to thefirst graphics request source.
 14. The system as recited in claim 9,wherein the one or more computing devices include further instructionsthat upon execution on or across the one or more processors furthercause the one or more computing devices to: cause a transformed versionof a first request packet originating at the graphics request source tobe delivered to a particular remote graphics processing device, whereinthe destination address of the first request packet differs from anaddress of the particular remote graphics processing device, and whereinthe destination address of the transformed version is the address of theparticular remote processing device.
 15. One or more non-transitorycomputer-accessible storage media storing program instructions that whenexecuted on or across one or more processors cause one or more computersystems to: obtain, from a client of the virtualized graphics servicevia a programmatic interface of the virtualized graphics service, arequest to establish an auto-scaled group to process requests from agraphics request source of the client, the request indicating aclient-specified scaling policy comprising one or more provisioningrules for adding or removing remote graphics processing devices to orfrom the auto-scaled group; identify, based at least in part on theclient-specified scaling policy, one or more remote graphics processingdevices of a network-accessible graphics computing service to processrequests from a graphics request source of the client as part of theauto-scaled group; cause one or more network connections to beestablished between the graphics request source and a first remotegraphics processing device of the one or more remote graphics processingdevices; and transmit, from the first remote graphics processing device,a result of a graphics operation requested by the graphics requestsource via the one or more network connections.
 16. The one or morenon-transitory computer-accessible storage media as recited in claim 15,wherein the client-specified scaling policy indicates that an exclusiveprovisioning mode is to be employed to assign remote graphics processingdevices, and wherein the one or more storage media store further programinstructions that when executed on or across the one or more processorsfurther cause the one or more computer systems to: reserve, inaccordance with the exclusive provisioning mode, the one or more remotegraphics processing devices for exclusive use by the graphics requestsource.
 17. The one or more non-transitory computer-accessible storagemedia as recited in claim 15, wherein the client-specified scalingpolicy indicates that a non-exclusive provisioning mode is to beemployed to assign remote graphics processing devices, and wherein theone or more storage media store further program instructions that whenexecuted on or across the one or more processors further cause the oneor more computer systems to: select, in accordance with thenon-exclusive provisioning mode, the one or more remote graphicsprocessing devices from a pool of remote graphics processing deviceswhich is shared among a plurality of graphics request sources.
 18. Theone or more non-transitory computer-accessible storage media as recitedin claim 15, wherein the client-specified scaling policy indicates aparticular category of a plurality of categories of remote graphicsprocessing devices of the graphics computing service, wherein theparticular category differs from another category of the plurality ofcategories in a performance capability, and wherein at least one remotegraphics processing device of the one or more remote graphics processingdevices belongs to the particular category.
 19. The one or morenon-transitory computer-accessible storage media as recited in claim 15,wherein the client-specified scaling policy indicates one or more rulesto be used to modify a number of remote graphics processing devicesassigned to the first graphics request source, and wherein the one ormore computing devices include further instructions that upon executionon or across the one or more processors further cause the one or morecomputing devices to: increase, in accordance with the one or morerules, a count of remote graphics processing devices assigned to thefirst graphics request source.
 20. The one or more non-transitorycomputer-accessible storage media as recited in claim 15, wherein theone or more computing devices include further instructions that uponexecution on or across the one or more processors further cause the oneor more computing devices to: cause a transformed version of a firstrequest packet originating at the graphics request source to bedelivered to a particular remote graphics processing device, wherein thedestination address of the first request packet differs from an addressof the particular remote graphics processing device, and wherein thedestination address of the transformed version is the address of theparticular remote processing device.